/Engine/Source/Editor/SceneOutliner/Public/ISceneOutlinerTreeItem.h
Flags structure
struct FlagsType
bool:  1
bChildrenRequireSort
True if this item's children need to be sorted
bool:  1
bInteractive
True if this item can be interacted with as per the current outliner filters
bool:  1
bIsExpanded
Whether this item is expanded or not
bool:  1
bIsFilteredOut
True if this item is filtered out